Android was made from linux.SteamOS is linux. Free to download and use as with every linux distro.This is a reason why Richard Stallman considers linux 'open-source' drool as poppycock. But it just happens thats its as real as it can get. Doom 3 was open-sourced. But that's Bulls**t. You cant go YAAAAAY!!..... when nothings being done to use code and linux in any real way.

Nvidia is a closed source company but they are the most non-hypocrite company around. Nay-say something but always do the right thing. They do believe in open-innovation.

AMD has Mantle up and ready for PC's --- linux/windows/maybe android. As carmack puts it; Mantle is a low level API that gives hardware resources directly to games and bypassing directX/Opengl....should provide further Boost to SteamOS.

Whether or not Nvidia's support for SteamOS is a publicity stunt or not, i guarantee they will do the right thing. Whether or not MANTLE is open source for now is speculation. If Nvidia accepts it, i see no reason for any superiority from AMD but instead healthy competition.

Frostbite 3 engine(Battlefield 4) will use Mantle.

Mantle will also unify the video game arena. It wont matter what hardware or OS you use in the coming future.

AAA titles will come to steam. Game devs will work in tandem with steam devs along with Nvidia and AMD starting from the ground up; the goal being -- to hell with underlying OS and hardware.Nvidia is leading even though AMD owns everything.